A voltage-controlled oscillator (VCO) is an electronic circuit that produces an oscillating signal with a frequency that is related to a control voltage applied at the input of the VCO. VCOs typically include an inductance/capacitance (LC) tank circuit having at least one variable capacitor, or varactor. Varactors are voltage-tunable capacitors having a capacitance that varies as a function of the DC voltage across the varactor. The one or more varactors in the LC tank circuit typically help adjust the frequency of oscillation of the VCO in response to varying levels of the control voltage. VCOs are used within phase-locked loops (PLLs) for various applications, such as wired and wireless communications.